Sheet hold-down device for presses



Jan. 12, 1943. 0. i=2 ROOT 2,303,308

SHEET HOLD-DOWN DEVICE FOR PRESSES FiiedFeb. 24, 1940 3 Shets-Sheet 1 'INVENTOR. CHA'RLE? EROOT.

v CM I '4 i Qay Jan. 12, 194:3. c. F. ROOT I SHEET HOLD-flown DEVICE Fon .PRESSES Filed Fb. 24, 1949 s Sheets-Sheet; 2

\ NH'I INVENTOR.

CHAR LES F. ROOT.

ATTORNEYS I Jan. 12, 1943. c. F. ROOT SHEET HOLD-DOWN DEVICE FOR PRESSES 3 Sheets-Sheet Filed Feb. 24, 1940 LZVENTOR.

CHARLES FROOT.

ATTORNEY? Patented Jan. 12, 1943 SHEET HOLD-DOWN DEVICE FOR PRESSES Charles F. Root, Cleveland, Ohio, assignor to The Chandler & Price Company, Cleveland, Ohio, a

corporation of Ohio Application February 24, 1940, Serial No. 320,667

17 Claims.

This invention relates, as indicated, to sheet hold-down devices for presses and more particularly to devices for preventing edge curling of sheets on the platens of platen presses.

With the thinner sheet stocks such as onion skin considerable difliculty has been experienced in the past due to the curling of the edges of the sheet on the platen, such curling interfering with the automatic removal of the sheet. Generally, a thin sheet will lie flat until printed whereupon it will tend to curl up and prevent proper action of the sucker tip of the delivery arm. Similar difficulty is often experienced when embossing thin metal sheets and the like.

It is, therefore, a primary object of this invention to provide means whereby the curling of sheets on the platens of platen presses may be prevented.

A further object of this invention is to obtain the above end without interfering with the impression of the sheet and its subsequent removal from the platen.

Still another object is to provide such means which may also be readily aflixed on existing presses and easily adjusted or removed.

Other objects of this invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

The annexed drawings and the following description set forth in detail certain mechanism embodying the invention, such disclosed means constituting, however, but one of various mechanical forms in which the principle of the invention may be used.

In said, annexed drawings:

Fig. 1 is a side elevational view of a portion of a platen press showing the platen, rocker, and sheet removal means;

Fig. 2 is a fragmentary View similar to Fig. 1 but showing the relative position of the platen and associated parts just prior to the descent of the sheet removal means;

Fig. 3 is a view similar to Fig 1 but showing the platen in position for impression of the sheet by contact with the form (not shown) Fig. 4 is a top plan view of the platen;

Fig. 5 is a front elevational view of the platen;

Fig. 6 is a fragmentary sectional view along the line E6 on Fig. 5;

Fig. 7 is a view similar to 6 but showing the hold-down of this invention in retracted position;

Fig. 8 is a cross sectional view of the metal tape along the line 88 on Fig. 6;

Fig. 9 is a view of a portion of such holddown and its supporting bar taken along the line 99 on Fig. 4;

Fig. 10 is a fragmentary perspective view of the hold-down supporting bar;

Fig. 11 is a cross sectional view of the holddown actuating device taken along the line I I-| l on Fig. 13;

Fig. 12 is a cross sectional view along the line l2l2 on Fig. 11;

Fig. 13 is a top plan view of the hold-down actuating device taken along the line l3-I3 on Fig. 11;

Fig. 14 is a cross sectional view along the line l4l4 on Fig. 11;

Fig. 15 is a view similar to Fig. 11 but showing the position of the device when actuated by contact of the cam roller with the press frame; and

Fig. 16 is a fragmentary view taken along the line l6l6 on Fig. 3.

Referring now more specifically to said drawings and particularly Fig. 1, the rocker l supporting platen 2 is pivotally mounted in bearing 3 in the main frame 4. Sheet delivery means are shown with sucker tip 5 in the act of seizing a sheet from said platen. Conventional grippers 6 are elevated to permit removal of the sheet. Tympan bails l are shown in place. Mounted on bolt 8 is a bracket member 9 carrying a cam guide 10 the purpose of which will be explained below.

Referring now also to Figs. t and 5, a bar ll having offset ends is pivotally mounted in brackets l2 and I3 below the forward edge of said platen. Slidably mounted on said bar is a bracket 14 (Figs. 5-, 6, 7 and 9). Said bracket is retained in any desired position upon said supporting bar by means of the spring held metal ball l5 which is adapted to engage depressions IS in said bar. A channel-shaped member I1 is pivotally mounted at the upper end of said bracket and a flange It extends therefrom at approximately a right angle. A spring l9 attached by screw 20 to said bracket tends to push said channel-formed member ll out from said bracket. The hole 2| in said bracket serves to accommodate the upturned end of said spring when said spring end is forced close to said bracket. A metal tape 22, shown in cross section in Fig. 8, of convex transverse shape whereby it retains its position when extended, is inserted beneath pin 23 which passes through the opposite walls of said channel-formed member,

passed between the upper end of bracket member I4 and said channel-formed member and allowed to protrude from beneath said flange I8 which guides the same into a position substantial perpendicular to the channel-formed member. As best shown in Figs. 6 and '7 the upper portion of bracket I4 is of such length that the protruding portion 24 of said tape 22 is held against the upper surface of the platen 2. The end 25 of said tape is bent slightly upwardly to pass over the edge of a sheet of paper 25 without rufiling the same. Said tape may be extended to the position desired and then secured in such position by tightening nut 21 threaded on said pin 23, thus slightly compressing the side walls of said channel-formed member IT. A slot 28 in said channel-formed member facilitates such compression thereof. Bracket member I4 and its associated parts may be removed entirely from supporting bar H if desired by moving the same to the reduced section 25 of said bar, as shown in Figs. 4 and 9.

Sectu'ed by set screws to the end 30 of bar II which protrudes through bracket member I3 is an angular lug 3!. A torsional spring 32, whose ends bear on said lug and said bracket member respectively, tends to rotate said bar I I in a counterclockwise direction as viewed in Figs. 6 and 11 for example. Pivotally secured between legs 33, extending downwardly from said bracket I3, is a rocker arm 34 carrying a cam roller 35. The degree of pivotal action thereof permitted is limited by contact with shoulders 36 and 31. A second lug 33 is fixedly attached to bar II adjacent bracket I3 and by engagement with nose 39 of rocker arm 34 prevents torsional spring 32 from causing portion 24 of tape 22 from bearing too heavily on the said platen. A cavity 40 in said rocker arm contains a metal ball 4| for the purposes described below. The tail 42 of said rocker arm is adapted to engage the lower surface of cam I as the platen rocks toward the form.

The operation of the device as thus described will now be explained. The sheet of paper 26 is fed to the platen and held in place by the adjustable tabs 43 of grippers 6. At the time that the sheet is being placed upon the platen cam roller 35 bearing upon frame piece 44, as shown in Figs. 1 and 15, forces said nose 39 of rocker arm 34 upwards against lug 38, rotating bar I I in a clockwise direction, and thus retracting the forward portion 24 of tape 22 on the platen. As the platen tips toward the impression position, roller 35 is raised from frame piece 44 and the action of spring 32 tends to cause bar II to rotate and offset portion 25 of tape 22 to overlie the edge of the sheet. However, this action is prevented due to the fact that in the Fig. 1 position ball M has rolled in cavity 40 towards the nose of rocker arm 34. Thus, as the platen tips towards the impression position said ball is interposed and held between shoulder 36 of bracket member I3 and said rocker arm, and causes substantially the same relative positions thereof to be maintained as in Fig. l with only a small advance of the forward portion of the tape, henceforth referred to as the hold-down finger. As the platen continues to rock, however, the tail 42 of said rocker arm 34 engages cam guide I9 slightly depressing said tail against the impulse of torsional spring 32 and permitting the ball to roll toward said tail. The hold-down finger is retracted throughout such action. As a result of the above, the sheet is fed, gauged, and

the impression made without interference from said finger.

As the platen rocks back toward delivery position the tail 42 gradually escapes from cam I0 and the spring 32 causes said finger to overlie the edge of sheet 28 and prevent curling. This position is well exemplified in Fig. 2 which shows cam roller 35 about to contact frame piece 44 and sucker tip 5 approaching the platen in readiness to seize the sheet thereon. After the finger has been advanced the conventional grippers rise in the usual manner. Then cam roller 35 strikes frame piece 44 and the hold-down finger is retracted just as the sucker tip touches the sheet (Figs. 1 and 15), for removal of the printed sheet and feeding of a new sheet.

If it be desired to render the hold-down means of this invention temporarily inoperative this may be done by tightening screw 45, looking ball M in the forward end of cavity 40 and preventing advancement of the finger at any point of the printing cycle or unnecessary wear of the moving Darts when the bracket carrying the finger has been removed' The ball may likewise be locked in the end of the cavity toward the tail of member 34 if the operator so desires, permitting the finger to be advanced durim the time between when roller 35 loses contact with frame piece 44 and tail 42 engages cam ID, i. e. between the feeding and impression positions.

It will be seen that the objects of this invention have been achieved in a simple manner and an easily regulatable device provided which may be readily attached to standard models of platen presses.

Other modes of applying the principle of the invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

1. Sheet hold-down means for use with platen presses and the like comprising a finger adapted to be advanced over the surface of a platen and retain the forward edge portion of a sheet thereunder, and cam operated means for automati cally and slida-bly retracting said finger when the platen is in delivery position.

2. Sheet hold-down means for use with platen presses and the like comprising a finger adapted to be advanced over the surface of a platen and retain the forward edge portion of a sheet there under, and cam means operative to slidably retract said finger when the platen is in delivery and impression positions.

3. Sheet hold-down means for use with platen presses and the like comprising a shaft pivotally mounted adjacent the forward edge of the platen, a resilient finger mounted on said shaft and bearing on the surface of such platen, and cam means operative to rock said shaft and slidably retract said finger when such platen is in delivery and impression positions.

4. Sheet hold-down means for use with platen presses and the like comprising a shaft pivotally mounted adjacent the forward edge of the platen, a finger mounted on said shaft and extending over the surface of such platen, means tending to rotate said shaft to advance said finger on said platen, and cam means operative to rotate said shaft and slidably retract said finger when such platen is in delivery and impression positions.

5. Sheet hold-down means for use with platen presses and the like comprising a shaft pivotally mounted adjacent the forward edge of the platen, a bracket mounted on said shaft, a finger carried by said bracket and adapted to extend over the surface of such platen, resilient means tending to rotate said shaft to advance said finger over said platen, and cam means operative to rotate said shaft and slidably retract said finger when such platen is in delivery position.

6. Sheet hold-down means for use with platen presses and the like comprising a shaft pivotally mounted adjacent the forward edge of the platen, a bracket adjustably mounted on said shaft, a resilient finger carried by said bracket and adapted to extend over the surface of such platen, resilient means tending to rotate said shaft to advance said finger over said platen, and cam means operative to rotate said shaft and slidably retract said finger When such platen is in delivery and impression positions.

'7. Sheet hold-down means for use with platen presses and the like comprising a shaft pivotally mounted adjacent the forward edge of the platen, a bracket adjustably mounted on said shaft, a resilient finger carried by said bracket and adapted to extend over the surface of such platen, resilient means tending to rotate said shaft to advance said finger over said platen, cam means operative to rotate said shaft to retract said finger when such platen is in delivery position, locking means for holding said finger in substantially retracted position as such platen rocks from delivery to impression position, means for automatically releasing said locking means prior to said platen reaching impression position, and cam means operative on said shaft to maintain the retracted position of said finger when. such platen is in impression position but becoming inoperative as such platen rocks from impression to delivery position.

8. Sheet hold-down means for use with platen presses and the like comprising a shaft pivotally mounted adjacent and parallel to an edge of the platen, a bracket mounted on said shaft, and a finger slidably and extensibly mounted in said bracket and adapted to extend over the surface of such platen, said finger comprising a transversely curved metal tape.

9. Sheet hold-down means for use with platen presses and the like comprising a bracket, means for rocking said bracket, a finger carried by said bracket and. adapted to extend over the surface of such platen, said finger comprising a transversely curved metal strip, and resilient means operative to maintain said linger in constant contact with said platen as said bracket is rocked in a plane normal to the surface of such platen.

10. Sheet hold-down means for use with platen presses and the like comprising a bracket, means for rocking said bracket in a plane normal to the surface of the platen, an extensible finger carried by said bracket, and means for lockin said finger at a desired point of extension, said finger comprising a transversely curved metal strip.

11. Sheet hold-down means for use with platen presses and the like comprising a bracket, a finger extensibly mounted in said bracket, and resilient means acting on said finger tending to depress the same, said finger comprising a transversely curved metal strip having a raised end thereto.

12. Sheet hold-down means for platen presses and the like comprising a finger mounted adjacent the forward edge of such platen and adapted to be advanced over the surface of such platen and retain the edge portion of a sheet thereunder, and means automatically operative to slidably retract said finger on such platen.

13. Sheet hold-down means for platen presses adapted to prevent curling of a sheet subsequent to impression comprising a finger mounted adjacent the forward edge of such platen and adapted to overlie the forward edge of such sheet, and cam means actuated upon movement of such platen operative to slidably retract said finger when the platen is in impression and delivery positions.

14. A sheet hold-down device for platen presses and the like comprising a bracket, a curved guide member pivotally mounted on said bracket, a sheet confining finger slidably and extensibly carried in said guide member, and resilient means operative to maintain said finger in contact with such platen.

15. Sheet hold-down means for platen presses and the like comprising a finger mounted adjacent the forward edge of such platen and adapted to be advanced over the surface of such platen and retain the edge portion of a sheet thereunder, and means automatically operative to slidably retract said finger on such platen when the latter is in delivery and impression positions.

16. A sheet hold-down device for platen presses and the like comprising a bracket, a curved guide member pivotally mounted on said bracket, a sheet confining finger slidably and extensibly carried in said guide member, resilient means operative to maintain said finger in contact with such platen, and means automatically operative to rock said guide member in opposition to said resilient means and thereby retract said finger on such platen.

17. A sheet hold-down device for platen presses and the like comprising a bracket, a curved guide member pivotally mounted on said bracket, a sheet confining finger slidably and extensibly carried in said guide member, resilient means operative to maintain said finger in contact with such platen, and means automatically operative, when such platen is in delivery and impression positions, to rock said guide member in opposition to said resilient means and thereby retract said finger on such platen.

CHARLES F. ROOT. 

